Recently, speeding-up of the signals, and both density growth and high multi-stratification of the patterns are becoming necessary in electronic circuit boards of information and telecommunications equipments represented by computers and portable devices and electronic circuit boards of automobile-related equipments represented by ITS (Intelligent Transport System). Accordingly, upgrading of frequency (100 MHz or more) in fields such as information and telecommunications equipments is progressing. The property of low-dielectric loss is required to the film that is used for condensers, antenna modules and the like that are contained in these equipments. As one of proposals that dissolve the aforementioned demands, there is a film made of a liquid crystal polymer (liquid crystal polymer film).
The liquid crystal polymer film has a lot of advantages such as low water absorption and good dimensional stability in addition to the low-dielectric loss. However, the film has the following problems: the film is very easily oriented and has a large anisotropic nature (a difference between a TD direction and a MD direction) of the film properties. In order to dissolve the problems, particular methods for film production are proposed (see, for example, JP-A-2000-326405 (“JP-A” means unexamined published Japanese patent application) and JP-A-7-251438). However, these methods have disadvantages in consideration of very strict production condition and complicate operation. In addition, when a thin film is produced, it is very difficult to keep flatness of the film.
Various methods are used to dissolve the anisotropic nature at the time of film formation (see, for example, JP-B-5-38007 (“JP-B” means examined Japanese patent publication), JP-A-5-331275, WO00/68291). However, liquid crystal polymers that are obtained by these methods still have a problem in consideration of a large reduction in fluidity. From consideration of insufficiency of effect on reduction of anisotropy, there is a need to improve a liquid crystal polymer that is used as a resin for film production.